package demoLinkedList;

public class MyLinkedList {
    static class ListNode{
        public int val;
        public ListNode prev;
        ListNode next;

        public ListNode(int val) {
            this.val = val;
        }
    }

    public ListNode head;
    public ListNode last;

    //头插法
    public void addFirst(int data){
        ListNode node = new ListNode(data);
        if(head == null){
            head = node;
            last = node;
            return ;
        }
        node.next = head;
        head.prev = node;
        head = node;
    }

    //尾插法
    public void addLast(int data){
        ListNode node = new ListNode(data);
        if(head == null){
            head = last = node;
            return ;
        }
        last.next = node;
        node.prev = last;
        last = node;
    }

    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index,int data){
        if(index < 0 || index > size()){
            System.out.println("超出链表范围...");
            return ;
        }
        if(index == 0)addFirst(data);
        if(index == size())addLast(data);
        ListNode cur = head;
        ListNode node = new ListNode(data);
        for (int i = 0; i <= index; i++) {
            cur = cur.next;
        }
        node.next = cur;
        cur.prev.next = node;
        node = cur.prev;
        node.prev = cur.prev;
    }

    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        ListNode cur = head;
        while(cur != null){
            if(cur.val == key){
                return true;
            }
            cur = cur.next;
        }
        return false;
    }

    //得到单链表的长度
    public int size(){
        int count = 0;
        ListNode cur = head;
        while(cur != null){
            count++;
            cur = cur.next;
        }
        return count;
    }

    public void display(){
        ListNode cur = head;
        while(cur != null){
            System.out.print(cur.val + " ");
            cur = cur.next;
        }
        System.out.println();
    }

    //删除第一次出现关键字为key的节点
    public void remove(int key){
        ListNode cur = head;
        while(cur != null){
            if(cur.val == key){
               if(cur == head) {
                   head = cur.next;
                   if (head != null) {
                       head.prev = null;
                   } else {
                       last = null;
                   }
               }else{
                   cur.prev.next = cur.next;
                   if(cur.next == null){
                       last = cur.prev;
                   }else{
                       cur.next.prev = cur.prev;
                   }
                }
                return;
            }else{
                cur = cur.next;
            }
        }
    }

    //删除所有值为key的节点
    public void removeAllKey(int key){
        ListNode cur = head;
        while(cur != null){
            if(cur.val == key){
                if(cur == head) {
                    head = cur.next;
                    if (head != null) {
                        head.prev = null;
                    } else {
                        last = null;
                    }
                }else{
                    cur.prev.next = cur.next;
                    if(cur.next == null){
                        last = cur.prev;
                    }else{
                        cur.next.prev = cur.prev;
                    }
                }
            }
            cur = cur.next;
        }
    }

    public void clear(){
        ListNode cur = head;
        while(cur != null){
            ListNode curN = head.next;
            cur.next = null;
            cur.prev = null;
            cur = curN;
        }
        head = null;
        last = null;
    }

}
